Method and apparatus for optically measuring the heating value of a multi-component fuel gas using nir absorption spectroscopy

a fuel gas and heating value technology, applied in the field of physical properties of fluids, can solve the problems of improper charges, difficulty in continuously and accurately measuring, and disadvantage of both buyers and sellers, and achieve the effect of maintaining initial costs and maintenance costs low

US7248357B2Active Publication Date: 2007-07-24GAS TECH INST
16 Cites 23 Cited by

Patent Information

Authority / Receiving Office
US · United States
Patent Type
Patents(United States)
Current Assignee / Owner
Publication Date
2007-07-24

Smart Images

  • Figure 1
    Figure 1
  • Figure 2
    Figure 2
  • Figure 3
    Figure 3
Patent Text Reader

Abstract

A method and system for measuring heat energy of a combustible fluid in which light having wavelengths in the near-infrared is directed into a test cell containing the combustible fluid and portions of the light not absorbed by the combustible fluid and passing out of the cell are spatially dispersed by wavelength, forming a light spectrum that is projected onto a detector. The light spectrum is digitized and inputted into a data processing unit in which it is compared to the actual spectrum of the light source stored in the system to determine the absorbance spectrum of the combustible fluid. The system is spectrally calibrated by identifying known spectral features of the combustible gas absorbance spectrum. To correct for deviations in the original light source spectrum, a light source calibration system is employed. Upon determination of the absorbance spectrum of the combustible fluid, the heating value of the combustible fluid is determined by comparing the absorbance spectrum to a plurality of spectra located within an on-board database.
Need to check novelty before this filing date? Find Prior Art

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a method and apparatus for the measurement of a physical property of a fluid that is dependent upon a physical characteristic of at least one functional group and is related to the quantity of that functional group in the fluid. More particularly, this invention relates to the measurement of the heating value of a fuel gas at-line and in real time. Even more particularly, this invention relates to a method and apparatus for measuring the heating value of a combustible gaseous fuel mixture, including functional groups and molecules, using near infrared absorption spectroscopy.

[0003] 2. Description of Related Art

[0004] Historically, the heat energy content of a combustible fluid was determined by burning precisely defined amounts of the fluid, e.g. natural gas, to determine the amount of energy produced from the combustion. Other methods determined the concentration of each whole combustible compou...

Examples

Embodiment Construction

[0023]The invention claimed herein is a method and system for measuring the heating value of a combustible fluid, such as natural gas, containing a plurality of combustible components. The invention utilizes the relationship between absorption spectroscopy and heating value and / or composition of a gas mixture which enables the quick, accurate and cost-effective relay of information to the user. As previously indicated, the absorbance spectra of combustible fluids can be converted into usable properties such as heating value and / or composition. The system of this invention continuously acquires absorption spectra from gases in the near-infrared region. FIG. 1 shows two plots exhibiting the absorption spectra of several natural gas components at different near-infrared spectral regions. The plot on the left (a) (Goldstein et al., “Real-Time Optical BTU Measurement of Natural Gas at Line Pressure,” 4th International Symposium on Fluid Flow Measurement, Jun. 27-30, 1999) displays severa...